The invention disclosed herein relates generally to image recognition methods and systems, and more specifically to a simple, low cost edge extraction operator to convert gray scale information into binary edge information necessary to allow measurement and data acquisition.
A machine vision system is known which performs certain functions in the gray scale domain. After these functions have been performed, a technique to convert the gray scale information to useful binary information is needed to allow measurement and data acquisition of a scene.
The majority of a scene is frequently relatively uniform background around a single object of interest. In addition, much of the view of an object within its edges may be uniform and not useful for detection, recognition and inspection purposes. Thus, in many instances, only the location of the edges of an object is necessary for performance of a required task.
The applicant has devised a unique, simple and low cost technique which implements an edge extraction operator to convert the scene from gray scale to binary. The technique may be used to find the edges of any object, given raw gray scale data. It does not require user selection of parameters to determine edge detection, is highly speed efficient and may be implemented in hardware or software. The technique optimizes thresholding based on local scene illumination and has a high degree of tolerance to illumination changes and local variance. It is not dependent on the placement or size of windows used to qualify data in a scene, and may be used in whole or in part to determine simple thresholding as applied to raw gray scale data. Finally, the edge detection technique is direction independent.